1. Field of the Invention
This invention relates to an output control system for internal combustion engines for vehicles, which reduces output torque from the engine during starting of the vehicle with an accelerator pedal of the vehicle being stepped on when an automatic transmission of the engine is put in gear, to thereby reduce a gear-shifting shock.
2. Prior Art
Conventionally, there is known an engine output torque control system for an internal combustion engine with an automatic transmission and throttle valve-driving means for electrically controlling the opening of a throttle valve of the engine in response to stepping-on of an accelerator pedal of the vehicle. According to the control system, a desired output torque from the engine is calculated based on a gear shifting mode of the automatic transmission and an amount of stepping-on of the accelerator pedal, a desired opening of the throttle valve is calculated based on the calculated desired engine output torque and the rotational speed of the engine, and the throttle valve is controlled through the throttle valve-driving means such that the actual opening of the throttle valve becomes equal to the calculated desired opening, to thereby control the output torque from the engine.
An automotive vehicle with the above internal combustion engine and engine output control system installed therein is started from a standing position thereof, in such a manner that when the accelerator pedal is not stepped on, a shift lever of the automatic transmission is operated to change the shift position of the automatic transmission from a neutral (N) position or a parking (P) position to a drive (D) range or a reverse (R) range whereby the gear mechanism of the transmission is put in gear, i.e. a clutch thereof is engaged, and if the accelerator is then stepped on, the throttle valve is controlled to open in response to the amount of stepping-on of the accelerator pedal, so that a driving force is transmitted from the engine through the automatic transmission to driving wheels of the vehicle to start the vehicle.
However, if the accelerator pedal is suddenly or largely stepped on immediately after the gear mechanism is put in gear to start the vehicle, the output torque from the engine suddenly increases to cause a sudden change in the driving force, resulting in a large gear-shifting shock being given to the driver and passenger(s).
Such a gear-shifting shock can occur similarly even in the case where the shift position is changed to put the gear mechanism in gear in a state where the accelerator pedal has been stepped on.